In this season of gratitude, Bill Krissoff has a different notion of thankfulness than most of us.

He feels “very lucky” to have been able to drop his orthopedic practice in Truckee, Calif. (a ski town in the Sierra Nevada), enlist in the Navy, and deploy to a war zone to repair the broken bodies of Marines — all at an age when most other people are making retirement plans.

Bill and Christine Krissoff had a right to think their family had already sacrificed enough for the country. Both their sons Nathan and Austin “were heavily influenced by 9/11,” Krissoff recounts, and enlisted in the Marine Corps. The oldest, Nathan, a graduate of Williams College who was an accomplished piano player, a talented athlete and a natural leader, was killed in combat in Iraq in December 2006.

The idea came to Krissoff that he, too, wanted to serve the Marines, as a surgeon. Usually, as Krissoff says, “fathers inspire sons; in our case, I think sons inspired dad.”

Only at age 60, he was too old. He wanted to sign up with the Navy so he could care for Marines, but the Navy politely turned him down. His second choice, the Army, told him it would take at least a year for an age waiver.

Then the Krissoffs were invited to a small gathering with President George W. Bush, who was in the area meeting with families of the fallen. At the end, Bush asked if there was anything the White House could do. Krissoff said he wanted a waiver to serve in the Navy Medical Corps. The meeting was on a Tuesday. On Friday, Krissoff had his waiver.

He deployed in 2009 to western Iraq, where he engaged in mostly routine orthopedics, because the temperature of the war had declined so drastically. Krissoff returned home and almost immediately was asked if he wanted to go to Afghanistan. “It wasn’t the timing I was looking for,” he says, “but it was the location I was looking for.”

From February to September this year he was in Afghanistan, including several months at Camp Bastion in Helmand province, the busiest surgical facility in Afghanistan. He was near the tip of the spear of an often-miraculous effort to save soldiers and Marines with battlefield injuries. “If a Marine came to us alive, there was a 99 percent chance he’d leave our facility alive,” he says.

The military has learned best practices to give wounded troops a fighting chance. There’s improved care at the site of injury (with an emphasis on staunching bleeding, keeping an airway open and treating lung collapse) and rapid evacuation.

When injured troops arrived at Camp Bastion, they got damage-control surgery to preserve life and limb, “just stabilize and not overdo it,” as Krissoff puts it. It wasn’t easy seeing young men so grievously wounded. “If I never saw that again,” he says, “that’d be OK. On the other hand, it’s very rewarding to hear, on the other end, that they’re doing well.”

Not a week would go by when Krissoff didn’t meet a Marine who knew Nathan or Austin, his sons. “The Marines is a very small world; it really is a family,” he says. Krissoff set aside everything to be part of it. If you try to praise Krissoff, now age 64 and at the Naval Hospital at Camp Pendleton in Southern California, he’ll invariably reply that he is simply grateful for the opportunity.

He recalls treating a Marine corporal in Afghanistan who got shot in the upper arm. Krissoff operated on him and cleaned up the wound, then told him he’d have to recuperate back in the States. “He wouldn’t hear of it,” Krissoff chuckles. The corporal stayed at Camp Bastion a while and rejoined his unit. Krissoff heard he got shot a second time and went right back to his unit in Marja again.

Krissoff asks an awed question that could just as easily be applied to his family: “Where do we get these people?” Where, indeed?